1. Field of the Invention
The present invention relates to a method and apparatus for displaying images. More particularly, the present invention relates to a method and apparatus for displaying images based upon the brain's ability to perform binocular summation of differing images.
2. Related Art
Head-mounted display systems for displaying images to a user's eyes or eye are known. Conventional head-mounted display systems typically include a head-mounted portion, the head-mounted portion having image-generating devices for generating images viewable by the user. Head-mounted display systems are typically used to convey computer generated information, data from sensing devices, or programmed entertainment such as moving or still images, which are often accompanied by audio signals for reception by a user's ears. One such conventional head-mounted display system 10 is illustrated by FIGS. 1 and 2.
The conventional head-mounted display system 10 includes a head-mounted portion 12, which includes right and left image displays 16, 18 and right and left eyepiece optics 20, 22, for displaying images to a user's eyes 21, 23. A controller 25 conveys image signals to the head-mounted portion 12 via a cable 14, which right and left lines 24, 26 for conveying image signals to the right and left image displays 16, 18, respectively. The controller 25 is comprised of an image source 30, which transmits image data to a processor 28, which is then formatted for transmission to the right and left image displays 16, 18 via the lines 24, 26.
In the conventional head-mounted display system 10, the right and left image displays 16, 18 each display identical images to the right eye 21 and to the left eye 23 of a user—which is known as the “biocular” mode of displaying images. FIG. 3 illustrates a simplified example of the images displayed to the right eye 21 and the left eye 23 of a user of the conventional head-mounted display system 10. Because the images displayed to the right eye 21 and to the left eye 23 of the user are identical, the user's brain does not gain additional information from the use of two image displays above what could be obtained from the use of one image display. The information contained in the image displayed to one eye is therefore redundant to the image displayed to the other eye.
Because each of the user's eyes are presented identical images, both the right and the left image displays 16, 18 must be of relatively high resolution (i.e., having a high number of individual pixels per unit area) in order to display an image having a desired sharpness. Specifically, if an image of n×m resolution (i.e., an image formed from an n×m array of pixels) is desired to be perceived by the user's brain, each of the right and left image displays must include at least an n×m array of pixels. This is undesirable because the cost of image displays increases with increasing resolution. In addition, high resolution display signals require higher storage and processing capabilities, which further adds to the cost of the head-mounted display system 10.
An alternative conventional head-mounted display is disclosed in U.S. Pat. No. 5,726,670 to Tabata et al. Tabata discloses increasing the resolution of selected portions of a display by using multiple display apparatuses to convey overlapping images. As illustrated by FIG. 1 of Tabata, separate images (b) and (c) are combined via differing optical paths to form an image (d). While the desired degree of resolution is obtained in image (b), Tabata's apparatus requires multiple optical systems to convey the overlapping images.
Therefore, a need exists for a method of displaying images that provides an image of desired resolution, and that is not unduly expensive. A need also exists for an apparatus for displaying images of desired resolution that is not unduly expensive.